Vehicle vision system using kinematic model of vehicle motion

ABSTRACT

A vision system of a vehicle includes a camera disposed at the vehicle and having a field of view exterior of the vehicle. The camera is operable to capture frames of image data. Responsive to image processing by an image processor of captured image data, a control is operable to determine objects present in the field of view of the camera. Responsive to vehicle data, the control determines a vehicle motion vector during driving of the vehicle by a driver of the vehicle. The control determines movement of an object relative to the vehicle via image processing of at least two frames of captured image data during driving of the vehicle by the driver of the vehicle. The control compares the determined relative movement of the object to the determined vehicle motion vector, and responsive to the comparison, the control may determine a misalignment of the camera.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the filing benefits of U.S. provisional application Ser. No. 61/825,753, filed May 21, 2013, which is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a vehicle vision system for a vehicle and, more particularly, to a vehicle vision system that utilizes one or more cameras at a vehicle.

BACKGROUND OF THE INVENTION

Use of imaging sensors in vehicle imaging systems is common and known. Examples of such known systems are described in U.S. Pat. Nos. 5,949,331; 5,670,935; and/or 5,550,677, which are hereby incorporated herein by reference in their entireties.

SUMMARY OF THE INVENTION

The present invention provides a vision system or imaging system for a vehicle that utilizes one or more cameras (such as one or more CMOS cameras) to capture image data representative of images exterior of the vehicle, and determines a kinematic model of motion of the vehicle as the vehicle is driven along any path or route. The system determines the kinematic model based on inputs indicative of the vehicle steering angle and/or vehicle speed and/or vehicle geometries.

The cameras (such as one or more CMOS cameras) capture image data representative of images exterior of the vehicle, and provide the communication/data signals, including camera data or captured image data, that may be displayed at a display screen that is viewable by the driver of the vehicle, such as when the driver is backing up the vehicle, and that may be processed and, responsive to such image processing, the system may detect an object at or near the vehicle and in the path of travel of the vehicle, such as when the vehicle is backing up. The vision system may be operable to display a surround view or bird's eye view of the environment at or around or at least partially surrounding the subject or equipped vehicle, and the displayed image may include a displayed image representation of the subject vehicle.

According to an aspect of the present invention, a vision system of a vehicle includes at least one camera (such as a camera comprising a two dimensional array of photosensing pixels) disposed at the vehicle and having a field of view exterior of the vehicle (and may include a plurality of cameras, each having a respective field of view exterior of the vehicle, such as rearward, sideward and/or forward of the vehicle). The camera is operable to capture frames of image data. Responsive to image processing by an image processor of captured image data, a control is operable to determine objects present in the field of view of the camera. Responsive to vehicle data (such as steering information of the vehicle, speed of the vehicle and/or distance traveled by the vehicle or the like), the control determines a vehicle motion vector during driving of the vehicle by a driver of the vehicle. The control determines movement of an object (present in the field of view of the at least one camera) relative to the vehicle via image processing of at least two frames of captured image data during driving of the vehicle by the driver of the vehicle. The control compares the determined relative movement of the object to the determined vehicle motion vector, and responsive to the comparison, the control may determine a misalignment of the camera.

These and other objects, advantages, purposes and features of the present invention will become apparent upon review of the following specification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a vehicle with a vision system that incorporates cameras in accordance with the present invention;

FIG. 2 is a schematic showing the coordinate system and angles used to represent the travel of the vehicle;

FIG. 3 is a schematic and block diagram of the system of the present invention; and

FIG. 4 is a model of the kinematic equations of the system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle vision system and/or driver assist system and/or object detection system and/or alert system operates to capture images exterior of the vehicle and may process the captured image data to display images and to detect objects at or near the vehicle and in the predicted path of the vehicle, such as to assist a driver of the vehicle in maneuvering the vehicle in a rearward direction. The vision system includes an image processor or image processing system that is operable to receive image data from one or more cameras and provide an output to a display device for displaying images representative of the captured image data. Optionally, the vision system may provide a top down or bird's eye or surround view display and may provide a displayed image that is representative of the subject vehicle, and optionally with the displayed image being customized to at least partially correspond to the actual subject vehicle.

Referring now to the drawings and the illustrative embodiments depicted therein, a vehicle 10 includes an imaging system or vision system 12 that includes at least one exterior facing imaging sensor or camera, such as a rearward facing imaging sensor or camera 14 a (and the system may optionally include multiple exterior facing imaging sensors or cameras, such as a forwardly facing camera 14 b at the front (or at the windshield) of the vehicle, and a sidewardly/rearwardly facing camera 14 c, 14 d at respective sides of the vehicle), which captures images exterior of the vehicle, with the camera having a lens for focusing images at or onto an imaging array or imaging plane or imager of the camera (FIG. 1). The vision system 12 includes a control or electronic control unit (ECU) or processor 18 that is operable to process image data captured by the cameras and may provide displayed images at a display device 16 for viewing by the driver of the vehicle (although shown in FIG. 1 as being part of or incorporated in or at an interior rearview mirror assembly 20 of the vehicle, the control and/or the display device may be disposed elsewhere at or in the vehicle). The cameras operate to capture frames of image data at a desired or selected frame rate, such as, for example, about 30 frames per second or more or less. The data transfer or signal communication from the camera to the ECU may comprise any suitable data or communication link, such as a vehicle network bus or the like of the equipped vehicle.

The kinematic model of the present invention generates a Motion Vector V_(1N)=(x_(1N), y_(1N), ψ_(1N)) of a moving vehicle between frame 1 and frame N, where x_(1N) and y_(1N) (mm) are the translational components of V and ψ_(1N) (degrees) is the heading angle of the vehicle. No specific vehicle motion is required, whereby the Motion Vector estimation is performed as the vehicle navigates along an arbitrary path.

The Kinematic Model of the present invention uses a “Bicycle Model” to represent the vehicle motion, and determines or computes elementary vectors V_(ij)=(x_(ij), y_(ij), ψ_(ij)) for each pair of frames i and j. The resulting motion vector is composed of elementary vectors.

The Kinematic Model of the present invention does not use any image information, and the inputs of the Kinematic Model include vehicle CAN bus data and vehicle geometry.

The kinematic model of the present invention develops numerical relations between wheel steering angles, wheel pulses, heading angle ψ_(ij) and translational vehicle motion x_(ij), y_(ij) between frames i and j. The system is operable to approximate the vehicle Kinematic Model by use of a bicycle kinematic model, where two front (and rear) wheels coincide (see, for example, FIG. 2). Experiments show that vehicle motion (such as four wheel vehicles, such as cars, vans, SUVs, trucks and/or the like) can be accurately described by such a bicycle kinematic model.

The Kinematic Model of the present invention provides a model of vehicle motion between frames, based on one or more system inputs. The system is operable to estimate a vector V_(ij)=(x_(ij), y_(ij), ψ_(ij)) of vehicle motion between image frames i and j. The inputs may provide input data, such as, for example, CAN bus vehicle motion data, such as, for example, the steering wheel angle and wheel pulse clicks and/or the like (see FIG. 3).

The kinematic modeling system of the present invention uses lateral vehicle dynamics and wheel pulse counters, and develops numerical relations between the wheel steering angles, the heading angle and the translational vehicle motion. The system uses the assumption that the motion of the vehicle can be accurately described by a Bicycle Model, where the two front and two rear wheels coincide (see FIG. 4).

The system of the present invention thus may determine a model of the motion or path of the vehicle responsive to vehicle system inputs, such as inputs from or indicative of the vehicle steering wheel angle and/or vehicle speed and/or the like. The system may utilize the motion model for camera calibration systems and/or the like, such as for a camera calibration system of the types described in U.S. patent application Ser. No. 14/282,028, filed May 20, 2014 by Galina Okouneva for VEHICLE VISION SYSTEM WITH TARGETLESS CAMERA calibration and published Nov. 27, 2014 as U.S. Publication No. US-2014-0347486, and U.S. provisional applications, Ser. No. 61/878,877, filed Sep. 17, 2013, and Ser. No. 61/825,752, filed May 21, 2013, which are hereby incorporated herein by reference in their entireties.

Optionally, the vision system (utilizing the forward facing camera and a rearward facing camera and other cameras disposed at the vehicle with exterior fields of view) may be part of or may provide a display of a top-down view or birds-eye view system of the vehicle or a surround view at the vehicle, such as by utilizing aspects of the vision systems described in International Publication Nos. WO 2010/099416; WO 2011/028686; WO2012/075250; WO 2013/019795; WO 2012/075250; WO 2012/145822; WO 2013/081985; WO 2013/086249; and/or WO 2013/109869, and/or U.S. patent application Ser. No. 13/333,337, filed Dec. 21, 2011, which are hereby incorporated herein by reference in their entireties.

In multi-camera surround view systems, maintaining calibration of the cameras is important. For example, a camera located at the outside mirror should be calibrated along with a camera located at the front or rear of the vehicle, so that the overlapping portions of the captured images can be properly stitched together to provide a substantially seamless top view or surround view display. Prior calibration methods are known, such as described in U.S. Pat. No. 7,720,580, which is hereby incorporated herein by reference in its entirety.

In accordance with the present invention, a vehicle data-based kinematic model of the equipped vehicle is determined as that vehicle travels a particular road or route, using vehicle data, such as including vehicle steering information, vehicle speed information, vehicle distance information and/or the like. Such vehicle data is supplied to a control (typically vehicle a CAN or LIN bus of the vehicle), which determines or establishes a vehicle-based motion vector for the vehicle at any given time and location along the driven route. In parallel (such as at the same time as the kinematic model is being determined), an image-based motion vector of that moving vehicle may be determined, based on change or movement of an imaged object between a first frame and a following or subsequent second frame.

In a properly calibrated system, movement of the equipped vehicle and objects in the field of view of the camera as determined via image processing of captured image data should coincide with and be the same as movement of the vehicle determined and predicted via the vehicle data based kinematic model. In other words, the kinematic model can be used to determine how an object present in the field of view of the camera may move relative to the vehicle as the vehicle is driven, and when the camera is properly calibrated, the location and movement of the object as determined via image processing of subsequent frames of captured image data should coincide with the predicted location and movement of the object as determined via use of the kinematic model. However, if a particular camera capturing image data processed in the first and second frames of captured image data is no longer properly calibrated, the motion of the object predicted by use of the vehicle kinematic vector determined by the vehicle data based kinematic model will be different than the relative motion of the object in the field of view of the misaligned camera as captured over two or more frames of image data. Thus, the control can determine and utilize this determined difference to establish or determine that an out of calibration condition of the subject vehicle camera exists. Responsive to such a determination, the system may adjust the camera calibration accordingly to bring the camera into calibration so as to have the location and relative movement of detected objects coincide with the predicted location and movement based on the actual kinematic/orientation of the equipped vehicle.

The camera or sensor may comprise any suitable camera or sensor. Optionally, the camera may comprise a “smart camera” that includes the imaging sensor array and associated circuitry and image processing circuitry and electrical connectors and the like as part of a camera module, such as by utilizing aspects of the vision systems described in International Publication Nos. WO 2013/081984 and/or WO 2013/081985, which are hereby incorporated herein by reference in their entireties.

The system includes an image processor operable to process image data captured by the camera or cameras, such as for detecting objects or other vehicles or pedestrians or the like in the field of view of one or more of the cameras. For example, the image processor may comprise an EyeQ2 or EyeQ3 image processing chip available from Mobileye Vision Technologies Ltd. of Jerusalem, Israel, and may include object detection software (such as the types described in U.S. Pat. Nos. 7,855,755; 7,720,580; and/or 7,038,577, which are hereby incorporated herein by reference in their entireties), and may analyze image data to detect vehicles and/or other objects. Responsive to such image processing, and when an object or other vehicle is detected, the system may generate an alert to the driver of the vehicle and/or may generate an overlay at the displayed image to highlight or enhance display of the detected object or vehicle, in order to enhance the driver's awareness of the detected object or vehicle or hazardous condition during a driving maneuver of the equipped vehicle.

The vehicle may include any type of sensor or sensors, such as imaging sensors or radar sensors or lidar sensors or ladar sensors or ultrasonic sensors or the like. The imaging sensor or camera may capture image data for image processing and may comprise any suitable camera or sensing device, such as, for example, a two dimensional array of a plurality of photosensor elements arranged in at least 640 columns and 480 rows (at least a 640×480 imaging array, such as a megapixel imaging array or the like), with a respective lens focusing images onto respective portions of the array. The photosensor array may comprise a plurality of photosensor elements arranged in a photosensor array having rows and columns. Preferably, the imaging array has at least 300,000 photosensor elements or pixels, more preferably at least 500,000 photosensor elements or pixels and more preferably at least 1 million photosensor elements or pixels. The imaging array may capture color image data, such as via spectral filtering at the array, such as via an RGB (red, green and blue) filter or via a red/red complement filter or such as via an RCC (red, clear, clear) filter or the like. The logic and control circuit of the imaging sensor may function in any known manner, and the image processing and algorithmic processing may comprise any suitable means for processing the images and/or image data.

For example, the vision system and/or processing and/or camera and/or circuitry may utilize aspects described in U.S. Pat. Nos. 7,005,974; 5,760,962; 5,877,897; 5,796,094; 5,949,331; 6,222,447; 6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202; 6,201,642; 6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452; 6,822,563; 6,891,563; 6,946,978; 7,859,565; 5,550,677; 5,670,935; 6,636,258; 7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,295,229; 7,301,466; 7,592,928; 7,881,496; 7,720,580; 7,038,577; 6,882,287; 5,929,786 and/or 5,786,772, and/or International Publication Nos. WO 2011/028686; WO 2010/099416; WO 2012/061567; WO 2012/068331; WO 2012/075250; WO 2012/103193; WO 2012/0116043; WO 2012/0145313; WO 2012/0145501; WO 2012/145818; WO 2012/145822; WO 2012/158167; WO 2012/075250; WO 2012/0116043; WO 2012/0145501; WO 2012/154919; WO 2013/019707; WO 2013/016409; WO 2013/019795; WO 2013/067083; WO 2013/070539; WO 2013/043661; WO 2013/048994; WO 2013/063014, WO 2013/081984; WO 2013/081985; WO 2013/074604; WO 2013/086249; WO 2013/103548; WO 2013/109869; WO 2013/123161; WO 2013/126715; WO 2013/043661 and/or WO 2013/158592, which are all hereby incorporated herein by reference in their entireties. The system may communicate with other communication systems via any suitable means, such as by utilizing aspects of the systems described in International Publication Nos. WO/2010/144900; WO 2013/043661 and/or WO 2013/081985, and/or U.S. patent application Ser. No. 13/202,005, filed Aug. 17, 2011 and published Mar. 15, 2012 as U.S. Publication No. US-2012-0062743, which are hereby incorporated herein by reference in their entireties.

Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents. 

The invention claimed is:
 1. A vision system of a vehicle comprising: a camera disposed at a vehicle and having a field of view exterior of the vehicle; wherein said camera comprises a two dimensional array of a plurality of photosensing elements; wherein said camera is operable to capture frames of image data; a control, said control comprising an image processor operable to process image data captured by said camera; wherein, responsive to image processing of captured image data, said control is operable to determine objects present in the field of view of said camera; wherein, responsive to vehicle data, said control determines a vehicle motion vector during driving of the vehicle by a driver of the vehicle; wherein the vehicle data includes at least two of (i) steering information of the vehicle, (ii) speed of the vehicle and (iii) distance traveled by the vehicle; wherein said control determines movement of an object relative to the vehicle via image processing of at least two frames of captured image data during driving of the vehicle by the driver of the vehicle; wherein said control compares the determined relative movement of the object to the determined vehicle motion vector; and wherein, responsive to a difference between the determined relative movement of the object and the determined vehicle motion vector, said control determines a misalignment of said camera.
 2. The vision system of claim 1, wherein the vehicle data is communicated to the control via a communication bus of the vehicle.
 3. The vision system of claim 1, wherein a kinematic model comprising a bicycle model is used to represent vehicle motion.
 4. The vision system of claim 3, wherein said kinematic model utilizes at least one of (i) a wheel steering angle, (ii) a wheel pulse, (iii) a heading angle and (iv) translational vehicle motion.
 5. The vision system of claim 1, wherein the vehicle data includes (i) steering information of the vehicle, (ii) speed of the vehicle and (iii) distance traveled by the vehicle.
 6. The vision system of claim 1, wherein, responsive to a determined misalignment of said camera, said vision system is operable to calibrate said camera.
 7. The vision system of claim 1, wherein said control compares the determined vehicle motion vector to an object vector determined between a first position of the object captured in a first frame of image data and a second position of the object captured in a second frame of image data.
 8. The vision system of claim 7, wherein said control determines a misalignment of said camera responsive to a difference between a direction or magnitude of the determined vehicle motion vector and a direction or magnitude of the determined object vector.
 9. The vision system of claim 1, wherein said vision system comprises a plurality of cameras disposed at the vehicle, each having a respective field of view exterior of the vehicle.
 10. The vision system of claim 9, wherein image data captured by at least some of said plurality of cameras is used for a surround view system of the vehicle.
 11. The vision system of claim 10, wherein said plurality of cameras comprises (i) a rear camera disposed at a rear portion of the vehicle and having a rearward field of view, (ii) a driver side camera disposed at a driver side exterior rearview mirror assembly of the vehicle and at least having a generally sideward and rearward field of view and (iii) a passenger side camera disposed at a passenger side exterior rearview mirror assembly of the vehicle and at least having a generally sideward and rearward field of view.
 12. The vision system of claim 1, wherein said camera comprises a CMOS camera.
 13. A vision system of a vehicle comprising: a plurality of cameras disposed at a vehicle, each having a respective field of view exterior of the vehicle; wherein said plurality of cameras comprises (i) a rear camera disposed at a rear portion of the vehicle and having a rearward field of view, (ii) a driver side camera disposed at a driver side of the vehicle and at least having a generally sideward and rearward field of view and (iii) a passenger side camera disposed at a passenger side of the vehicle and at least having a generally sideward and rearward field of view; wherein said cameras are operable to capture frames of image data; a control, said control comprising an image processor operable to process image data captured by said cameras; wherein, responsive to image processing of captured image data, said control is operable to determine objects present in the fields of view of said cameras; wherein, responsive to vehicle data, said control determines a vehicle motion vector during driving of the vehicle by a driver of the vehicle; wherein the vehicle data includes at least two of (i) steering information of the vehicle, (ii) speed of the vehicle and (iii) distance traveled by the vehicle; wherein said control determines movement of an object relative to the vehicle via image processing of at least two frames of image data captured by at least one of said cameras during driving of the vehicle by the driver of the vehicle; wherein said control compares the determined relative movement of the object to the determined vehicle motion vector; and wherein, responsive to a difference between the determined relative movement of the object and the determined vehicle motion vector, said control determines a misalignment of said at least one of said cameras.
 14. The vision system of claim 13, wherein each of said cameras comprises a two dimensional array of a plurality of photosensing elements.
 15. The vision system of claim 13, wherein the vehicle data is communicated to the control via a communication bus of the vehicle.
 16. The vision system of claim 13, wherein, responsive to a determined misalignment of said at least one of said cameras, said vision system is operable to calibrate said at least one of said cameras.
 17. The vision system of claim 13, wherein said control compares the determined vehicle motion vector to an object vector determined between a first position of the object captured in a first frame of image data by said at least one of said cameras and a second position of the object captured in a second frame of image data by said at least one of said cameras.
 18. The vision system of claim 17, wherein said control determines a misalignment of said at least one of said cameras responsive to a difference between a direction or magnitude of the determined vehicle motion vector and a direction or magnitude of the determined object vector.
 19. A vision system of a vehicle comprising: a plurality of cameras disposed at a vehicle, each having a respective field of view exterior of the vehicle; wherein said plurality of cameras comprises (i) a rear camera disposed at a rear portion of the vehicle and having a rearward field of view, (ii) a driver side camera disposed at a driver side of the vehicle and at least having a generally sideward and rearward field of view and (iii) a passenger side camera disposed at a passenger side of the vehicle and at least having a generally sideward and rearward field of view; wherein each of said cameras comprises a two dimensional array of a plurality of photosensing elements; wherein said cameras are operable to capture frames of image data; a control, said control comprising an image processor operable to process image data captured by said cameras; wherein, responsive to image processing of captured image data, said control is operable to determine objects present in the fields of view of said cameras; wherein, responsive to vehicle data, said control determines a vehicle motion vector during driving of the vehicle by a driver of the vehicle; wherein the vehicle data includes at least two of (i) steering information of the vehicle, (ii) speed of the vehicle and (iii) distance traveled by the vehicle; wherein the vehicle data is communicated to the control via a communication bus of the vehicle; wherein said control determines movement of an object relative to the vehicle via image processing of at least two frames of image data captured by at least one of said cameras during driving of the vehicle by the driver of the vehicle; wherein said control compares the determined relative movement of the object to the determined vehicle motion vector; wherein, responsive to a difference between the determined relative movement of the object and the determined vehicle motion vector, said control determines a misalignment of said at least one of said cameras; and wherein, responsive to a determined misalignment of said at least one of said cameras, said vision system is operable to calibrate said at least one of said cameras.
 20. The vision system of claim 19, wherein said control compares the determined vehicle motion vector to an object vector determined between a first position of the object captured in a first frame of image data by said at least one of said cameras and a second position of the object captured in a second frame of image data by said at least one of said cameras, and wherein said control determines a misalignment of said at least one of said cameras responsive to a difference between a direction or magnitude of the determined vehicle motion vector and a direction or magnitude of the determined object vector. 